Asteroids

[kiwi]

an update from January of P/2010 A2....

The aftermath of a huge collision between two asteroids from the same batch of space rocks which wiped out the dinosaurs has been captured by NASA scientists.
They slammed into each other at about 11,000mph - creating an explosion as powerful as a small atomic bomb - 90 million miles away from earth.
The cosmic pile-up between the orbits of Mars and Jupiter is the first ever witnessed and could lead to new ways of preventing another asteroid slamming into our planet.......


Either the impact did not have enough power to pulverize the original rock into very small grains or the tail's relatively large particles predate the impact - implying small asteroids such as P/2010 A2 are accumulations of gravel.....


Dr Nesvorny said: 'Further investigation should be carried out to distinguish between the two options. After all, asteroids can bump into all sorts of things, and before they do, we had better know what they are made of.'


Read more: http://www.dailymail.co.uk/sciencetech/ ... z12QTiM4TZ




Prof Jewitt said: 'We thought that this event had just occurred. We expected the debris field to expand dramatically, like shrapnel flying from a hand grenade.
'So we rushed to apply for Hubble time to watch the aftermath. But what happened was quite the opposite. We found that the object is expanding very, very slowly and that it started not a week, but nearly a year before our January observations.'



Read more: http://www.dailymail.co.uk/sciencetech/ ... z12QSjdCqC



Read more: http://www.dailymail.co.uk/sciencetech/ ... z12QSUA1id

[mharratsc]

Talk about your preconceptions clouding your vision!

This is what they said about their 'non-expanding debris field':

"We expected the debris field to expand dramatically, like shrapnel flying from a hand grenade," Jewitt said. "But what happened was quite the opposite. We found that the object is expanding very, very slowly."

Does this look like expansion to anyone? Here's the time-lapse image set for the object (big pic so I posted a link to it):

http://i.space.com/images/asteroid-coll ... 013-02.jpg

It looks to me like the object is disintegrating with every frame. Doesn't look a damn bit different than a comet or meteor burning up to me.

[FS3]

Sure. Asteroids do dream of Comets. More often than the usual "collisionists" would like:



Bigger pic HERE


Btw. - What's the difference between an egg?

FS3

[kschalm]

good post, nick. i was going to point that out myself until i saw you'd done it. somebody needs to explain to Snodgrass what "directly observed" means.

Particle sizes in the tail are estimated to vary from about 1 millimetre to 2.5 centimetres in diameter.
...
Radiation pressure from the Sun then swept the debris behind the remnant asteroid, forming a comet-like tail.

http://www.dailymail.co.uk/sciencetech/ ... z12QTiM4TZ

that's asking a lot from radiation pressure.

Alice laughed. `There's no use trying,' she said `one
can't believe impossible things.'

`I daresay you haven't had much practice,' said the Queen. `When I was
your age, I always did it for half an hour a day. Why, sometimes I've
believed as many as six impossible things before breakfast.

[nick c]

This thread is a compilation of the following threads:

X shaped asteroid

asteroid seismology question

Why is there an asteroid belt?

Itokawa asteroid dust and satellite Hayabusa

It's official: An asteroid wiped out the dinosaurs

Double body asteroid proof for Barbara (asteroid 234)

Rosetta`s asteroid flybys

Asteroid switched Mars's magnetic field on and off

[StefanR]

When is an Asteroid Not an Asteroid?

Vesta is most commonly called an asteroid because it lies in the orbiting rubble patch known as the main asteroid belt between Mars and Jupiter. But the vast majority of objects in the main belt are lightweights, 100-kilometers-wide (about 60-miles wide) or smaller, compared with Vesta, which is about 530 kilometers (330 miles) across on average. In fact, numerous bits of Vesta ejected by collisions with other objects have been identified in the main belt.

"I don't think Vesta should be called an asteroid," said Tom McCord, a Dawn co-investigator based at the Bear Fight Institute, Winthrop, Wash. "Not only is Vesta so much larger, but it's an evolved object, unlike most things we call asteroids."

The layered structure of Vesta (core, mantle and crust) is the key trait that makes Vesta more like planets such as Earth, Venus and Mars than the other asteroids, McCord said. Like the planets, Vesta had sufficient radioactive material inside when it coalesced, releasing heat that melted rock and enabled lighter layers to float to the outside. Scientists call this process differentiation.

McCord and colleagues were the first to discover that Vesta was likely differentiated when special detectors on their telescopes in 1972 picked up the signature of basalt. That meant that the body had to have melted at one time.

Officially, Vesta is a "minor planet" -- a body that orbits the sun but is not a proper planet or comet. But there are more than 540,000 minor planets in our solar system, so the label doesn't give Vesta much distinction. Dwarf planets – which include Dawn's second destination, Ceres -- are another category, but Vesta doesn't qualify as one of those. For one thing, Vesta isn't quite large enough.

Dawn scientists prefer to think of Vesta as a protoplanet because it is a dense, layered body that orbits the sun and began in the same fashion as Mercury, Venus, Earth and Mars, but somehow never fully developed. In the swinging early history of the solar system, objects became planets by merging with other Vesta-sized objects. But Vesta never found a partner during the big dance, and the critical time passed. It may have had to do with the nearby presence of Jupiter, the neighborhood's gravitational superpower, disturbing the orbits of objects and hogging the dance partners.

Other space rocks have collided with Vesta and knocked off bits of it. Those became debris in the asteroid belt known as Vestoids, and even hundreds of meteorites that have ended up on Earth. But Vesta never collided with something of sufficient size to disrupt it, and it remained intact. As a result, Vesta is a time capsule from that earlier era.

"This gritty little protoplanet has survived bombardment in the asteroid belt for over 4.5 billion years, making its surface possibly the oldest planetary surface in the solar system," said Christopher Russell, Dawn's principal investigator, based at UCLA. "Studying Vesta will enable us to write a much better history of the solar system's turbulent youth."

Dawn's scientists and engineers have designed a master plan to investigate these special features of Vesta. When Dawn arrives at Vesta in July, the south pole will be in full sunlight, giving scientists a clear view of a huge crater at the south pole. That crater may reveal the layer cake of materials inside Vesta that will tell us how the body evolved after formation. The orbit design allows Dawn to map new terrain as the seasons progress over its 12-month visit. The spacecraft will make many measurements, including high-resolution data on surface composition, topography and texture. The spacecraft will also measure the tug of Vesta's gravity to learn more about its internal structure.

http://dawn.jpl.nasa.gov/feature_storie ... ersary.asp

[seasmith]

Other space rocks have collided with Vesta and knocked off bits of it. Those became debris in the asteroid belt known as Vestoids, and even hundreds of meteorites that have ended up on Earth. But Vesta never collided with something of sufficient size to disrupt it, and it remained intact

.

OR, it could just as likely be that those other similar "bits" were splatter formed when Vesta was spun off or ejected as a fluid plasmoid,
or separated from an already separated Vesta, in its plasmoid state.

Guess we'll see from the pictures if they were cookie or dough ...




http://dawn.jpl.nasa.gov/feature_storie ... ersary.asp

[kmerrell]

NASA’s Near Earth Objects Program (NEO) detected a large asteroid known as 2005 YU55 approaching Earth to about 0.85 lunar distances (200,000 kilometres) on November 8 and 9, 2011.

Read more: http://www.digitaljournal.com/article/3 ... z1LbF9yxdY

While traditional sky watchers are breathing a sigh of relief that YU55 won't impact earth isn't there a possibility of some sort of electrical interaction between us and the visitor?

[mharratsc]

I'm going to hazard the *guess* (guess, mind you) that it probably won't be all that electrically dynamic.

Here's why:

Unlike a long period comet, the asteroid belt is just on the other side of our near neighbor, Mars. Most of the planets are pretty much in electrical equilibrium these days. The plasmatails of the planets have been brushing around on close passes of planets with their neighbors and providing paths for charge equalization, and I would presume that Mars' plasmatail somehow manages to negotiate it's way through all the asteroids to equalize with Jupiter, so all the asteroids would therefore be pretty much balanced out with Mars and so we shouldn't expect any of the more extreme issues we see with the 'greater' comets (such as some of the earthquake events that were seen to seemingly coincide with the orbital alignment of the Sun, the Earth, and Comet Elenin).

Therefore, I would suggest that - although there may be some minor cometary display from the asteroid - it won't be anything near what we see from more energetic comets.

Let's see if I'm right here in the near future, I guess.

[StefanR]

Three days after the outburst was announced, Swift's Ultraviolet/Optical Telescope (UVOT) captured multiple images and a spectrum of the asteroid. Ultraviolet sunlight breaks up the gas molecules surrounding comets; water, for example, is transformed into hydroxyl and hydrogen. But none of the emissions most commonly identified in comets, such as hydroxyl or cyanogen, show up in the UVOT spectrum. The absence of gas around Scheila led the Swift team to reject scenarios where exposed ice accounted for the activity.

Images show the asteroid was flanked in the north by a bright dust plume and in the south by a fainter one. The dual plumes formed as small dust particles excavated by the impact were pushed away from the asteroid by sunlight. Hubble observed the asteroid's fading dust cloud on Dec. 27, 2010, and Jan. 4, 2011.

The two teams found the observations were best explained by a collision with a small asteroid impacting Scheila's surface at an angle of less than 30 degrees, leaving a crater 1,000 feet across. Laboratory experiments show a more direct strike probably wouldn't have produced two distinct dust plumes. The researchers estimated the crash ejected more than 660,000 tons of dust -- equivalent to nearly twice the mass of the Empire State Building.

"The dust cloud around Scheila could be 10,000 times as massive as the one ejected from comet 9P/Tempel 1 during NASA's UMD-led Deep Impact mission," said co-author Michael Kelley, also at the University of Maryland. "Collisions allow us to peek inside comets and asteroids. Ejecta kicked up by Deep Impact contained lots of ice, and the absence of ice in Scheila's interior shows that it's entirely unlike comets."

http://www.nasa.gov/topics/universe/fea ... ision.html

On December 11, 2010, an otherwise nondescript asteroid named Scheila brightened suddenly. In addition, the asteroid showed evidence of plume-like jets of gas emanating from its surface. It was almost as if this asteroid was transforming itself into a comet. Comets and asteroids are two separate categories of objects, of course: comets are huge interplanetary snowballs, while asteroids are giant rocks hurtling through space. But we know now that some asteroids apparently have substantial pockets of ice and other volatile materials below the surface, and in rare instances this material can become exposed and blow off the surface when heated by the sun. To see if this was happening, astronomers trained the Ultraviolet and Optical Telescope (UVOT) aboard the Swift spacecraft observatory at Scheila, and, a few days later, the cameras on the Hubble Space Telescope. The UVOT image of Scheila is shown above. The image of the comet was overexposed to reveal faint dust plumes in the optical and UV image. A spectrum of the asteroid obtained by the UVOT showed no evidence of water, indicating that the ejected material was not due to exposed water ice. The combined Hubble and Swift observations show that the December 11 brightening was most probably due to an 11,000 mile per hour collision between a small asteroid and Scheila. Images of craters on asteroids give mute testimony to the occurrence of ancient collisions; this is the first time such a young collision has been seen in near real-time. A deeper impact?

http://heasarc.gsfc.nasa.gov/docs/objec ... swift.html

[GaryN]

Getting closer.
NASA's Dawn Captures First Image of Nearing Asteroid

I think the framing camera is very interesting, particularly the optics.

[larryduane100]

Wow! ASTEROID FLYBY: Newly-discovered asteroid 2011 MD will pass only 12,000 kilometers (7,500 miles) above Earth's surface on Monday, June 27th. NASA analysts say there is no chance the space rock will strike Earth. Nevertheless, the encounter is so close that Earth's gravity will sharply perturb the asteroid's trajectory. Details at http://spaceweather.com

There should be some plasma effects.
Larry White

[Sparky]

Hey, Larry...you said, "There should be some plasma effects."

Possibly...it is my understanding that charge differential would depend on the obit of the asteroid. If it does not get very far from the sun, there may not be enough of a charge difference to notice, even at such a close distance. There could be a discharge if it entered earth's magnetosphere.

That will be a close flyby!

[Lloyd]

* Did the asteroid hit anything? Hello? Is anyone out there?

[Eaol]

I saw nothing.